You will get this if you play on Veteran difficulty but I suggest playing on Supersoldier difficulty as the achievement is stackable and if you follow the guide below, it should be pretty simple.
Tip: Play through the game on the easiest difficulty first and upgrade your suit so that it drains less energy when you both run and are in Stealth mode, then start a new campaign and you will keep your suit upgrades, now run past every firefight that you possibly can.
I ran through many missions without even shooting a single shot. The video shows the only part that I had a little trouble with, but I easily beat it with this video. Good luck!